While it is important to experimentally determine at what scales we can confirm that gravity behaves as expected in Newtonian gravity and general relativity, nobody had any good reason to think that it would break down at short distances on the order of roughly a 200th of a millimeter or longer.
Any short distance, weak field quantum gravity effects wouldn't be expected at any scale significantly above the femtometer scale and possibly only at a scale comparable to the Planck length, which are many, many orders of magnitude smaller.
New Test of the GravitationalLaw at Separations down to 52 m(Submitted on 26 Feb 2020)We tested the gravitationallaw using a stationary torsion-balance detector and a rotating attractor containing test bodies with both 18-fold and 120-fold azimuthal symmetries that simultaneously tests the law at two different length scales. We took data at detector-attractor separations between m and 3.0 mm. Newtonian gravity gave an excellent fit to our data, limiting with 95\% confidence any gravitational-strength Yukawa interactions to ranges m.